Normally in modern Redis you can't create zero-len lists, however it's
possible to load them from old RDB files generated, for instance, using
Redis 2.8 (see issue #4409). The "Right Thing" would be not loading such
lists at all, but this requires to hook in rdb.c random places in a not
great way, for a problem that is at this point, at best, minor.
Here in this commit instead I just fix the fact that zero length lists,
materialized as quicklists with the first node set to NULL, were
iterated in the wrong way while they are saved, leading to a crash.
The other parts of the list implementation are apparently able to deal
with empty lists correctly, even if they are no longer a thing.
Normally in modern Redis you can't create zero-len lists, however it's
possible to load them from old RDB files generated, for instance, using
Redis 2.8 (see issue #4409). The "Right Thing" would be not loading such
lists at all, but this requires to hook in rdb.c random places in a not
great way, for a problem that is at this point, at best, minor.
Here in this commit instead I just fix the fact that zero length lists,
materialized as quicklists with the first node set to NULL, were
iterated in the wrong way while they are saved, leading to a crash.
The other parts of the list implementation are apparently able to deal
with empty lists correctly, even if they are no longer a thing.
Normally in modern Redis you can't create zero-len lists, however it's
possible to load them from old RDB files generated, for instance, using
Redis 2.8 (see issue #4409). The "Right Thing" would be not loading such
lists at all, but this requires to hook in rdb.c random places in a not
great way, for a problem that is at this point, at best, minor.
Here in this commit instead I just fix the fact that zero length lists,
materialized as quicklists with the first node set to NULL, were
iterated in the wrong way while they are saved, leading to a crash.
The other parts of the list implementation are apparently able to deal
with empty lists correctly, even if they are no longer a thing.
Since SDS v2, we no longer have a single header, so the function to
rewrite the SDS in terms of the minimum space required, instead of just
using realloc() and let the underlying allocator decide what to do,
was doing an allocation + copy every time the minimum possible header
needed to represent the string was different than the current one.
This could be often a bit wasteful, because if we go, for instance, from
the 32 bit fields header to the 16 bit fields header, the overhead of
the header is normally very small. With this commit we call realloc
instead, unless the change in header size is very significant in relation
to the string length.
Since SDS v2, we no longer have a single header, so the function to
rewrite the SDS in terms of the minimum space required, instead of just
using realloc() and let the underlying allocator decide what to do,
was doing an allocation + copy every time the minimum possible header
needed to represent the string was different than the current one.
This could be often a bit wasteful, because if we go, for instance, from
the 32 bit fields header to the 16 bit fields header, the overhead of
the header is normally very small. With this commit we call realloc
instead, unless the change in header size is very significant in relation
to the string length.
Since SDS v2, we no longer have a single header, so the function to
rewrite the SDS in terms of the minimum space required, instead of just
using realloc() and let the underlying allocator decide what to do,
was doing an allocation + copy every time the minimum possible header
needed to represent the string was different than the current one.
This could be often a bit wasteful, because if we go, for instance, from
the 32 bit fields header to the 16 bit fields header, the overhead of
the header is normally very small. With this commit we call realloc
instead, unless the change in header size is very significant in relation
to the string length.
When we free the backlog, we should use a new
replication ID and clear the ID2. Since without
backlog we can not increment master_repl_offset
even do write commands, that may lead to inconsistency
when we try to connect a "slave-before" master
(if this master is our slave before, our replid
equals the master's replid2). As the master have our
history, so we can match the master's replid2 and
second_replid_offset, that make partial sync work,
but the data is inconsistent.
When we free the backlog, we should use a new
replication ID and clear the ID2. Since without
backlog we can not increment master_repl_offset
even do write commands, that may lead to inconsistency
when we try to connect a "slave-before" master
(if this master is our slave before, our replid
equals the master's replid2). As the master have our
history, so we can match the master's replid2 and
second_replid_offset, that make partial sync work,
but the data is inconsistent.
When we free the backlog, we should use a new
replication ID and clear the ID2. Since without
backlog we can not increment master_repl_offset
even do write commands, that may lead to inconsistency
when we try to connect a "slave-before" master
(if this master is our slave before, our replid
equals the master's replid2). As the master have our
history, so we can match the master's replid2 and
second_replid_offset, that make partial sync work,
but the data is inconsistent.
There was not enough sanity checking in the code loading the slots of
Redis Cluster from the nodes.conf file, this resulted into the
attacker's ability to write data at random addresses in the process
memory, by manipulating the index of the array. The bug seems
exploitable using the following techique: the config file may be altered so
that one of the nodes gets, as node ID (which is the first field inside the
structure) some data that is actually executable: then by writing this
address in selected places, this node ID part can be executed after a
jump. So it is mostly just a matter of effort in order to exploit the
bug. In practice however the issue is not very critical because the
bug requires an unprivileged user to be able to modify the Redis cluster
nodes configuration, and at the same time this should result in some
gain. However Redis normally is unprivileged as well. Yet much better to
have this fixed indeed.
Fix#4278.
There was not enough sanity checking in the code loading the slots of
Redis Cluster from the nodes.conf file, this resulted into the
attacker's ability to write data at random addresses in the process
memory, by manipulating the index of the array. The bug seems
exploitable using the following techique: the config file may be altered so
that one of the nodes gets, as node ID (which is the first field inside the
structure) some data that is actually executable: then by writing this
address in selected places, this node ID part can be executed after a
jump. So it is mostly just a matter of effort in order to exploit the
bug. In practice however the issue is not very critical because the
bug requires an unprivileged user to be able to modify the Redis cluster
nodes configuration, and at the same time this should result in some
gain. However Redis normally is unprivileged as well. Yet much better to
have this fixed indeed.
Fix#4278.
There was not enough sanity checking in the code loading the slots of
Redis Cluster from the nodes.conf file, this resulted into the
attacker's ability to write data at random addresses in the process
memory, by manipulating the index of the array. The bug seems
exploitable using the following techique: the config file may be altered so
that one of the nodes gets, as node ID (which is the first field inside the
structure) some data that is actually executable: then by writing this
address in selected places, this node ID part can be executed after a
jump. So it is mostly just a matter of effort in order to exploit the
bug. In practice however the issue is not very critical because the
bug requires an unprivileged user to be able to modify the Redis cluster
nodes configuration, and at the same time this should result in some
gain. However Redis normally is unprivileged as well. Yet much better to
have this fixed indeed.
Fix#4278.
Certain checks were useless, at the same time certain malformed inputs
were accepted without problems (emtpy strings parsed as zero).
Cases where strtod() returns ERANGE but we still want to parse the input
where ok in getDoubleFromObject() but not in the long variant.
As a side effect of these fixes, this commit fixes#4391.
Certain checks were useless, at the same time certain malformed inputs
were accepted without problems (emtpy strings parsed as zero).
Cases where strtod() returns ERANGE but we still want to parse the input
where ok in getDoubleFromObject() but not in the long variant.
As a side effect of these fixes, this commit fixes#4391.
Certain checks were useless, at the same time certain malformed inputs
were accepted without problems (emtpy strings parsed as zero).
Cases where strtod() returns ERANGE but we still want to parse the input
where ok in getDoubleFromObject() but not in the long variant.
As a side effect of these fixes, this commit fixes#4391.
